Splicing connectors for cables and electrical connectors, commonly referred to as automatic splices, have long been known, and are used by utility linemen to quickly splice lengths of suspended cable together.
The automatic splice has become a mainstay in the electrical utility industry. Originally developed for “emergency restoration”, it has evolved into a nominal construction component for overhead power lines, and has been extensively used in the industry for approximately 70 years. With the major evolution to the use of aluminum conductors several decades ago, automatic splices were developed for aluminum conductors.
Aluminum, while more economical for construction, suffers more problems associated with corrosion and degradation of the electrical interface over time, in comparison to copper. Over the decades, due principally to economics and market competition, connectors, along with most products, have been “optimized” to be produced with the minimal amount of material required, the least amount of labor and finish, and designed to minimal performance standards to remain economically viable in the market. Such has been the case with automatic splices.
In particular, in corrosive environments, such as coastal areas, aluminum connectors of all types experience a reduction in service life. This reduction has been particularly prevalent with aluminum automatic splices. Along with the aging infrastructure, an abundance of catastrophic failures of aluminum automatic splices in such environments has led a number of electrical utilities which operate and maintain overhead electrical lines in these areas to remove aluminum automatic splices from their approved standards, thus prohibiting their installation in the corrosive environments.
Furthermore, in recognition of the many aluminum automatic splices installed heretofore, with their eminent premature failure approaching, some utilities have initiated in-service replacement programs. The most common conductor splice, heretofore favored as being the most robust in corrosive environments, is the standard compression splice. However, the labor and time, and thus the cost of making live line splices with compression tools is unreasonably prohibitive. Such programs often include cost estimates exceeding twenty times that of installation of automatic splices.
The market has recognized that the view of economics based on purchasing less robust splices with shorter life spans has been a poor choice for the long term. Utilities, which have come to realize this situation, have requested that a more robust automatic splice be developed which will withstand numerous fault currents over time, and resist the corrosion elements of coastal environments. Therefore, an analysis of the principal design shortcomings resulting from economic suppression was conducted, as well as analysis of failure modes and solutions.
The traditional design of automatic splices has been refined by economics, and has resulted in a splice tube body of minimal cross section, sufficient only to withstand the tensile load which could be applied by the conductor for which the splice is designed, along with a marginal safety factor. Thus, the addition of openings in the body of conventional splice designs would violate the required tensile strength.
Due to economics, the springs used in traditional automatic splices, used for the purpose of biasing the jaws into engagement with the conductor, have been made from steel plates. The plating on such springs does not last long, and consequently, rust begins to form, adding to the corrosive contaminants inside the splice body.
Analysis of the failure mode of aluminum automatics reveals the potential for corrosive elements to build up within the architecture of the device. In application, a catenary is formed when a conductor is suspended under tension between adjacent structures. The automatic splice serves to join two conductors at a location within this span. Therefore, there always exists a portion of conductor located above the position of the splice. As the prominent conductor is constructed with a plurality of strands, wound in a helical manner, it is impractical to attempt to seal the entry port of the connector about the periphery of the conductor, as the interstitial area between the strands will remain as a conduit for moisture to enter the splice body.
Pollutants and particulate matter settle on the conductor during dry periods, along with salt buildup in saline environments typical of those in coastal areas. In addition, during particularly foggy conditions, the salt fog enters into the body of the automatic splice, due to its open architecture. Rain and other precipitation will carry the aforesaid pollutants and particulate matter into the splice from the portion of exposed conductor which is above the position of the splice. Subsequently, following the precipitation event, temperature rise within the automatic splice occurs due to electrical current and solar gain, resulting in evaporation of the water, leaving the corrosive components inside the splice. The warm environment inside the splice contributes to the corrosive action.
In response to this recognition, certain devices have been designed to better withstand the rigors of the environment into which these splices are placed. U.S. Pat. No. 6,796,854 to Mello et al. represents a variation of U.S. Pat. No. 6,773,311 to Mello et al. providing an open architecture body such that contaminants do not build up within.
Accordingly, a need exists for an easy to use corrosion resistant splice that is resistant to line disturbances caused by wind and ice. Also, a need exists for a splice having features to promote the expulsion of corrosive components from the interior of the splice.